EP2815840A1 - Soldering of steels and component - Google Patents

Abstract

By using nickel-based solder, very high soldering temperatures and correspondingly long holding times, a very good structural connection between steels is achieved.

Description

The invention relates to joining by means of high-temperature brazing of steels and a component.

Steels are usually joined via welding processes.

Soldering is an alternative, but the solder joint must have good mechanical properties for LCF stress or other stresses to be used in highly stressed areas.

It is therefore an object of the invention to show a structural soldering that solves the above problem.

The object is achieved by a method according to claim 1 and a component according to claim 12.

In the dependent claims further advantageous measures are listed, which can be combined with each other in order to achieve further advantages.

The advantage of the invention lies in the easy to carry out soldering of steels with very good mechanical properties in the Fügeung for the component.

The description is only exemplary embodiments of the invention.

Steels which can be joined by means of the process according to the invention are not subject to any restriction, but in particular the process is suitable for low-alloyed ferritic steels or steels with molybdenum, in particular 16 mol.

• ein Kohlenstoffanteil (C) von 0,12Gew.-% - 0,2Gew.-%,
• ein Siliziumanteil (Si) < 0,35Gew.-%,
• ein Mangananteil (Mn) von 0,4Gew.-% - 0,9Gew.-%,
• ein Phosphoranteil (P) von max. 0,025 sowie
• einen maximalen Schwefelgehalt (S) von 0,01Gew.-%,
• ein Chromanteil (Cr) liegt bei ≤ 0,3 Gew.-%,
• ein Molybdängehalt (Mo) liegt zwischen 0,25 - 0,35 Gew.-%, ein Gehalt an Nickel (Ni) kann bis zu 0,3Gew.-% betragen und Vanadium (V) mit einem Anteil bis 0,02Gew.-%,
  wobei Werte für Kupfer (Cu) bis 0,3Gew.-%,
  für Stickstoff (N) bis 0,012Gew.-% und
  für Niob (Nb) bis 0,02Gew.-% zugelassen sind.

The 16Mo3 steel has:

• a carbon content (C) of 0.12 wt% -0.2 wt%,
• a silicon content (Si) <0.35 wt%,
• a manganese content (Mn) of 0.4% by weight - 0.9% by weight,
• a phosphorus content (P) of max. 0.025 as well
• a maximum sulfur content (S) of 0.01% by weight,
• a chromium content (Cr) is ≦ 0.3% by weight,
• a molybdenum content (Mo) is between 0.25 and 0.35% by weight, a content of nickel (Ni) may be up to 0.3% by weight and vanadium (V) with a proportion of up to 0.02% by weight. %
  where values for copper (Cu) are up to 0.3% by weight,
  for nitrogen (N) to 0.012 wt .-% and
  for niobium (Nb) up to 0.02% by weight.

Preferably, the steel silicon (Si), the proportion of which is significantly, in particular 3 times above the detection limit.

Preferably, the steel nickel (Ni), the proportion of which is distinct, in particular 3 times above the detection limit.

Preferably, the steel has vanadium (V), the proportion of which is distinct, in particular 3 times, above the detection limit.

Preferably, the steel has chromium (Cr), the proportion of which is distinct, in particular 3 times, above the detection limit.

Preferably, the steel copper (Cu), the proportion of which is significantly, in particular 3 times above the detection limit.

In particular, the invention relates to the joining of identical or the same steels.

As the solder material between the steels, a nickel-based alloy is used.

The solder material preferably has a high chromium content (Cr), preferably from 18% by weight to 20% by weight and / or one high silicon content (Si) of at least 6 wt .-% to.

Preferably, the chromium content (Cr) of the solder material is 19% by weight.

The carbon content (C) of the solder material may be at 0.1 wt% maximum or is 0.08 wt .-%.

An advantageous solder material has a silicon content (Si) of 7% by weight to 10% by weight.

By adding boron (B), the silicon content (Si) can be reduced, so that when the silicon content (Si) is 7.3% by weight, a boron content (B) of 1.5% by weight is used.

In particular, films or powders can be used to apply the solder material between the steel components.

The gaps between the steel components to be joined should be small, ≤ 80 μm, in particular ≤ 50 μm.

For surface activation, various methods are preferably used; in particular, irradiation with SiC spheres takes place.

An essential point of the joining process lies in the soldering temperature, which is preferably at temperatures> 1150 ° C, in particular greater than 1185 ° C and thus significantly above the usual soldering temperatures for steels.

The soldering temperature is preferably between 1150 ° C and 1215 ° C,
in particular between 1180 ° C and 1210 ° C,
especially at 1195 ° C.

The holding time at soldering temperature is at least 20 minutes, in particular at least 40 minutes, and thus significantly above the standard holding times for brazing for steels of about 10 minutes.

Further preferred value ranges for the holding time at the soldering temperature are between 20 min and 120 min, in particular between 40 min and 100 min, very particularly at 90 min.

• Zum Löten werden die zu fügenden Komponenten auf 600°C mit einer Rate von 6,4K/min hochgeheizt und ggf. noch 10 Minuten gehalten,
• darauf weiterhin folgt ein Hochheizen auf 1050°C mit einer Rate von 5K/min. und ebenfalls einer optionalen Haltezeit von 10 Minuten,
• danach wird die maximale Löttemperatur, vorzugsweise von 1195°C vorzugsweise mit einer Rate von 4,1K/min. erreicht, gefolgt von einer Haltezeit von 90min,
• danach erfolgt vorzugsweise direkt anschließend ein Abkühlprozess auf 723°C vorzugsweise mit einer Abkühlrate von 23,5K/min. und einer optionalen Haltezeit dort von 60 Minuten,
• danach können die verbundenen Komponenten wieder erhitzt werden mit einer Rate von 14K/min. auf eine Temperatur von 933°C mit einer optionalen Haltezeit von 10 Minuten,
• danach wird auf 50°C vorzugsweise durch erzwungene Abkühlung abgekühlt.

An exemplary soldering cycle is:

• For soldering, the components to be joined are heated to 600 ° C. at a rate of 6.4 K / min and, if appropriate, kept for 10 minutes,
• this is followed by a heating up to 1050 ° C at a rate of 5K / min. and also an optional hold time of 10 minutes,
• thereafter, the maximum brazing temperature, preferably 1195 ° C, preferably at a rate of 4.1K / min. reached, followed by a hold time of 90min,
• Thereafter, preferably followed directly by a cooling process to 723 ° C, preferably at a cooling rate of 23.5 K / min. and an optional hold time of 60 minutes,
• after that, the connected components can be reheated at a rate of 14K / min. to a temperature of 933 ° C with an optional hold time of 10 minutes,
• then it is cooled to 50 ° C, preferably by forced cooling.

• Als weitere Schritte nach dem Löten folgt Normalisieren, gefolgt von Abschrecken, wobei das Normalisieren erfolgt, um die Kornvergröberung im Grundmaterial zu reversieren.

In general:

• Further steps after brazing are followed by normalization followed by quenching, with normalization being done to reverse grain coarsening in the base material.

Thus, good cyclic mechanical properties are produced, if desired. The curing is required to obtain a certain degree of hardening.

In addition, a coating heat treatment may be downstream.

Preferably, alitization is performed after soldering.

Solder seams between steels are produced with the described process methods. In the test, it has been found that the material test samples in the base material and not in the solder joint fail, so that the soldering for structural joints can be used.

Claims (20)

method
for brazing steels
in which a Nickelbasislot between two steel components is used as the solder material. Method according to claim 1,
in which the solder is applied as a foil or as a powder between the two steel components. Method according to one or both of claims 1 or 2, wherein the soldering gap between the two steel components
≤ 80μm,
in particular ≤ 50 microns. Method according to one or more of the preceding claims 1, 2 or 3,
in which the soldering temperature is at least 1150 ° C, in particular at least 1160 ° C,
especially at at least 1180 ° C,
lies. Method according to one or more of the preceding claims 1, 2 or 3,
in which the soldering temperature between 1150 ° C and 1215 ° C, in particular between 1180 ° C and 1210 ° C,
especially at 1195 ° C
lies. Method according to one or more of the preceding claims 1, 2, 3, 4 or 5,
in which the holding time at the soldering temperature is at least 20 minutes,
especially at least 40 minutes,
especially at least 80 minutes,
lies. Method according to one or more of the preceding claims 1, 2, 3, 4 or 5,
in which the holding time at the soldering temperature between 20min and 120min,
especially between 40min and 100min,
especially 90min,
is. Method according to one or more of the preceding claims,
in which annealing takes place after brazing, especially at 723 ° C for steel components comprising 16Mo3. Method according to one or more of the preceding claims,
in which a normalization is carried out after brazing, in particular at 933 ° C for steel components having 16Mo3. Method according to one or more of the preceding claims,
in which a quenching takes place after the soldering. Method according to one or more of the following claims 1 to 10,
in which after the brazing a coating heat treatment takes place. Component made of two steel components,
which are joined together by a Nickelbasislot. Component according to claim 12,
in which the nickel bond between the steel components has a width of ≤ 80 μm. Component or method according to one or more of the preceding claims 1 to 13,
in which the steel of the steel components is a low alloy ferritic steel or
a steel with molybdenum (Mo),
especially 16Mo3,
represents. Method or component according to one or more of claims 1 to 14,
wherein a nickel-chromium-silicon alloy (Ni-Cr-Si) is present as a solder material between the steel components. Method or component according to one or more of the claims,
in which the chromium content (Cr) of the solder material is 18% by weight to 20% by weight,
in particular 19% by weight. Method or component according to one or more of the claims,
in which the steel components have the same or the same material. Method or component according to one or more of the preceding claims,
in which the nickel-based solder has at least silicon (Si),
in particular with 7% by weight - 10% by weight of silicon (Si),
in particular 10% by weight of silicon (Si) and
optionally boron (B) with at least 1% by weight,
in particular with 1.5% by weight,
especially with 7.0 - 7.5 wt.% silicon (Si). Method or component according to one or more of the preceding claims,
in which the nickel-based solder has at least carbon (C),
in particular with at least 0.05% by weight of carbon (C). Method or component according to one or more of the preceding claims,
in which an alitization is performed after soldering or has.